(6ew) Complex and Biological Fluids

Research Interests: My research interest and expertise is in the emerging field of complex and biological fluids. The problems I am interested in also fall under the purview of soft and active matter. Many phenomena in nature involve a variety of forces that conspire together to show complex dynamics and even give rise to self-organisation, flocking and swarming. A large subset of these phenomena,for example, intracellular processes in living organisms, take place in a fluid medium where hydro-dynamic forces balance elastic, electric or magnetic forces. The main focus of my research has been to unravel and interpret these complex mechanisms using a variety of mathematical modelling and numerical techniques. Some questions that have fuelled my research work are: how do seemingly simple systems, living or synthetic, show self-organization or coherent motion at scales much larger than their individual size; how can we obtain macroscopic models from microscopic interactions at the individual level to explain such collective dynamics, how do microorganisms of increasing complexity perform locomotion in ingenious ways and how can we design synthetic microbots that mimic them. More recently, I have become interested in key questions in developmental cell biology that involve mechanical processes. Some of these questions are: what are the active forces arising from the motion of actin filaments or microtubules inside a cell that enables it to perform various important tasks, like migration,cell-division; how fluid-structure interaction due to ciliary motion inside oocytes enables organisms to have a left-right symmetry; how does tissue elongation occur due to cellular interactions. The common theme that triggers my interest in all these problems is the crucial role played by mechanics.

Complex Fluids: Complex fluids are found in abundance in both nature and industry. They comprise a class of fluids that are typically non-Newtonian in their behaviour. Examples include suspensions of colloidal particles, liquid drops or polymers suspended in a fluid. The application of thermal, magnetic or electric fields can alter the macrosopic properties of these fluids and render them non-Newtonian. My research work has focused on a part of this wide spectrum of complex fluids: multiphase flows and electro-rheological (ER) fluids. I will focus on a specific phenomena called as Quincke rotation, an instability under which dielectric particles or drops can spontaneously start rotating under the application of an electric field. Apart from having significance in colloidal hydrodynamics, this phenomena has seen a resurgence as it has proved to be an ideal system for making synthetic active matter.

Biological fluids: Locomotion at the microscale level has fascinated scientists since the last few decades. While larger organisms like fish and humans can take advantage of inertia to locomote, smaller organisms like
prokaryotes live in a world of low Reynolds numbers and cannot use inertia due to the well established Scallop theorem. In this section, I will focus on the hydrodynamics of bacteria and its interaction with the environment. Bacteria are found abundantly in nature and form an important part of the global ecosystem. It is crucial to understand their dynamics: how individual cells perform locomotion, how their colonies swarm and multiply eventually leading to formation of biofilm that has profound impact on food industry and understanding infectious diseases.

Teaching Interests: The core underlying philosophy that fuels my passion to teach and supervise students is to help them understand complex ideas that I have already understood and gained expertise in. My passion for teaching stems from the belief that it is a noble profession as it one of the best ways to contribute to a society's development and also have a sustainable positive influence on students that lasts a lifetime. Teaching also helps me in questioning and re-evaluating my own understanding of the subject. I have gained considerable teaching experience during my graduate and post-doctoral career spanning more than 8 years. I have designed and taught a course on fluid mechanics in the University of Illinois, Urbana-Champaign entirely on my own in the early stages of my graduate studies and served as a teaching assistant several times during the course of 3 years. During my postdoctoral career, I have supervised undergraduate students in Department of Applied Mathematics and Theoretical Physics, Cambridge and mentored an undergraduate student from Trinity College on a research project that I independently designed. Furthermore, I have also mentored PhD students in the biophysics/mechanics group on certain projects that have resulted in joint publications. I have also been involved in science festivals for public outreach held at the mathematics department in University of Cambridge.